if i download a a trial game that lasts 60 mins is there a way to get it off my puters memory so i can download it again

Only Windows reinstall seems to be the legal solution to me.

It is most likely added to your registry you should be able to edit the registry to remove the reference to the game,or use a registry editor to do it fo you .remember to backup the registry before you edit anything .
Please read info in the link below before you do anything .
http://cloanto.com/kb/3-151.html