Yes, absolutely you can. But try this to give yourself confidence: copy it off to a portable USB drive, then delete it. If you suspect problems result, you could always copy it back (but you never will)
Sofar SnagIt worked well. Yesterday I had CCLeaner cleanup local temp files and also the "Setup_Snagit_EVALUATION_ENU.msi" was cleaned up. When launching SnagIt today I got an error and had to re-install SnagIt again.
The setup file then was restored and SnagIt worked fine again.
So my experience: it seems the evaluation thing is necessary.