You need to hook up your N95 to your PC via the USB lead and access the data transfer mode, and you need to make sure your file explorer can view hidden folders.
You'll find the theme files in a folder named 'Private', in this folder are lots of other folders.
Go to the folder named '10207114' and then enter the folder inside called 'Import'In here are all the themes on your sd card.
You have to open every folder and then look in the skn folder to find the name of the theme as the folders are named by numbers and not the theme itself, if the PC doesn't allow you to open the file then choose to open it with Notepad, then scroll across until you see the name of the theme and usually it'll say the creator's name too.
Once you know it's the theme you want to delete then you have to delete the whole folder including the mbm,mif,ini and skn folders.
Author: Mr G from N95Users.com