Downsampling

Hiya!
After sending some recent work to my ME, I asked for some feedback. He told me that the mixes were pretty impressive and wondered why I recorded at 44.1 and not 88.2 or 96k. I told him simply because I use UAD plugs a lot and using a higher sampling rate would be too much of a headache.

He told me to record at a higher sampling rate and downsample when it comes time to mix.

How would I go about doing this. I use Sonar 7, and I'm not sure how to do this....