Q: Change my Computer Name

Hello,

I think you're refering to the Usernaname of the Home folder, which renaming can cause distaster, the actual omputer nane can easily be changed in Sytem Preferences>Sharing, but what exact OSX vetsion are you running?

Changing your home directory name is basically the same as moving your home directory.

Moving your home folder in OS X

If you attempt to do this you should first make sure you have a bootable backup of your current system.  Use a backup utility like Carbon Copy Cloner or Super Duper to "clone" your boot drive to another drive.  If anything goes wrong you can revert your original disk from the backup.

OS X: How to change user account name or home directory name