if it is dry, you are screwed, if it isnt, brake cleaner is agood solvent that breaks down adhesives rather nicely. I know it removes #77 spray glue rather well from todays experience //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
Just mix up a 80/20 solution of hydrogen peroxide and water solution. That is 80% water and 20% peroxide. Then let it sit for about 10-15 minutes and voila. You might be able to use a little more peroxide, it really depends on the color of the shirt though. Hope this helps