also, can i install a new theme over an old one?
What method of install are you using, Clockworkmod or SPRecovery? Really doesn't matter much but just move the old theme's "update" file and\or change the name back to original. D/L the new theme and follow the readme or install or OP. Do a backup first though so you can get back to where you were at least.
EDIT: If you want to remove the current theme and go back then do a recovery to where you were before installing the current theme.
Sent from my 'Simply Stunning' Droidafter
SS v.___what week is it? Chevyno1 is awesome
1.0 ghz lv kernel
Every time I add anything (new rom, theme, kernel) I make a backup that way I can simple restore to any of the previous selections that I installed.