Of course you can. Go to your replay folder in your toribash directory. (My Computer/C: Drive/Games/Toribash/Replays.) Once you're there, delete the replays you don't want.
But if u've instaled tb in another drive look for it there ........
I've 2 versions of tb 3.9and 3.91 beta instaled in 2 diferents drives (use the one on D) and when i opened drive C and tb replays couldn't find any of my replays .........