This is for Windows 7 (beyond like 8 or whatever I do not know).
Maybe I missed it, but I did not see what OS you are using. Anyway, if Windows 7 or beyond, just check the hard disk by clicking on Computer on the desktop and getting up the C:\ drive where the OS is, and right clicking and selecting Properties. There you will see Tools and Check Harddisk. Since it is the OS drive you will have to restart your computer and if any files are wrong or corrupted, then Windows will replace those before the computer starts up.
As for the ASIO4All I never used it, and would not know if any files are left over, and if it can be deleted like any regular program in Control Panel -> Programs and Features (or something like that where you un-install programs).
If not sure, then in Control Panel -> Administrative Tools -> System Configuration then you can start up the programs you want to start up and disable by unchecking the checkbox or stopping the program from starting up when the computer boots up. You can go and Start up the computer also in Minimal Mode and all of that also there in those Windows as well as processes from Microsoft or other programs you do not want to start up the computer with.
If ASIO4All left other files around, then you may have to use another program to see what leftover files are on the computer and have that program remove them if necessary.
You can use this program that may help for about 30 days and I have used it:
http://www.revouninstaller.com/revo_uninstaller_free_download.html on the bottom of that page you will see version 2.5.9 that can be downloaded. Not the latest version but it works, and may help.