This is important: http://www.dailyrindblog.com/technical-supporting-high-quality-audio/?utm_source=Sailthru&utm_medium=email&utm_campaign=Client%20Newsletter:%20week%20of%20May%2016%2C%202016&utm_term=All%20Clients%20%2B%20All%20Orchardites
 
The Orchard’s brand new standard audio specs are: WAV (.wav) / 16- or 24-bit / 44.1 kHz / Stereo.

• Be uniform when submitting your releases and avoid uploading a mix of 16-bit and 24-bit tracks on the same album.

I guess- this answers my question. So based on this article- can I say that I dont even need to turn it to 16 bit unless I make CD?
 
Then what would be the best way to make bith 24 and 16 bit files if I have Ozone? Thank you. 

I don't have Ozone, I do all of mastering inside SONAR and burn CD's in Sony's CD Architect.
 
If Orchard accept 24 bit files then I suggest you send them these. No need to worry about dithering down to 16 bit, this is ONLY for burning CD's (though these will play on almost anything)
 
Ozone must surely provide the option to export at 24 bit, so export from SONAR at 24 bit and you're good to go

Sonar and all wave editors allow you to save in just about any format. 
But the working environment these days is normally 24 bit. 
Sonar is working at 24 bit for me now since I bought the Tascam and then later the Scarlett. I think my M Audio interface ,10 years ago, was the only one that forced 16 bit. I think even my Sound friggin Blaster was 24 bit. 
 
Studios should be in the habit of keeping the highest quality master on hand. 
So there's no reason not to always have a 24 bit copy of each song on your album on hand. 
From there you can down grade them to Cd or MP3 as needed. 
I keep a main folder with sub folders inside for each mastered album. The sub folders contain the 16 bit or the 24 bit Wave and the MP3 version, I might have 2 Wave folders and 2 MP3 folders, one at 160 and one at 360.  
My old masters were all 24 bit but these day's I'm not recording anything important so all is just 16 bit from the minute I export from Sonar. 

vladasyn
Then what would be the best way to make bith 24 and 16 bit files if I have Ozone? Thank you. 

Might be something for you here:
http://forum.cakewalk.com/Ozonians-Dithering-question-m3380642.aspx

vladasyn
 How do you use 24 bit files? it would not even play on anything (or may be it only applies to 32 bit?.

Your audio interface is almost certainly converting 16bit to 24bit when you play a 16bit file through it.

It is almost certainly doing the analogue-digital conversion at 24bit when you record. It is Sonar that will then be following your instructions and reducing the 24 bit data it receives from the interface to 16 bit.

I say "almost certainly" because there may be an interface or sound-card somewhere that still uses 16 bit convertor chips, like CD players use. I'm just not aware of one that does, even the modern cheap on-board sound cards use 24 bit convertors.

As for 32 bit, no, many media players can't handle it. And there's no point in them being able to handle it. 32 bit audio can handle a dynamic range of 193dB, which from an audio point of view is pointless because there are very few things that are that loud - nuclear weapon tests, Krakatoa-scale volcanic eruptions, that kind of thing. 24 bit handles 145dB, which is fine for all real-world audio recording and playback.

32 bit data processing, which is what many DAWs do, or 64 bit, is useful because the DAW pads out the 16 or 24 bit audio with lots of zeros to get the higher bit depth, which means processing it can be done more accurately with fewer unwanted side-effects. But your audio hardware will almost certainly be playing the result to you at 24 bits because that's what the hardware handles.

Saving projects at 32 bit means that Sonar or whatever processes the audio next doesn't have to do a conversion from 24/16 bits up to whatever it handles then back down again so avoids some processing and some potential, but very minor, side-effects. Though those side-effects are generally inaudible to humans. 32 bit files do take up a great deal of disk space though.

As for dithering, I forget the details, but someone (Ethan Winer?) did a test involving a lot of experienced engineers to see if they could tell the difference between audio dithered down using different algorithms and no dithering at all. Generally speaking they couldn't, especially between the different algorithms.

Record at 24 bit and leave the final mixdown at 24 bit unless you're making an audio CD or you need to distribute it as a wave file that's as small as possible while retaining CD quality. For all other purposes there's little point in dithering a 24bit file to 16 bit. There's an argument for mastering for mp3 separately than for CD, FLAC and other formats because mp3 benefits if the master has two or three dB headroom rather than the common 0.3dB used for CD. Mp3 is also likely to change the sound of the audio, especially at lower conversion qualities, which may also make a dedicated mastering job advisable,

Apple's stuff about mastering for itunes has some useful things to say about mastering for compressed formats, including Apple's own lossless compression. The big emphasis is on avoiding digital clipping.