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There are a number of products that will remove tape and its glue from walls and other surfaces. Since plastic tape is somewhat resistant to solvents, the trick is to combine a solvent product and careful scraping with a single-edge razor (preferably in a razor blade holder).
Before you use the solvent, though, try just the razor! Some tapes will come off easily once you lift a corner... others won't... it is worth a try. Then, just use the solvent to remove any adhesive residue.
The solvents I have used successfully are generic denatured alcohol, "Goof Off", and "Wilbond". The last product is a well-known paint deglosser... also known as "liquid sandpaper". If your walls are painted with latex paint, be aware that all of these products will remove some or all of the paint from the area treated, depending on the amount of rubbing. This is not a problem if you are planning to repaint.
(Note: There is another popular "goo" remover known as "Goo Gone" I do not recommend for this task because it is oil rather than solvent based. This might cause a paint adhesion problem.)
The method for "tough" tapes is straightforward. Apply some solvent to the tape. Use the razor to lift an edge of the tape... then slide the razor blade underneath the tape. Apply more solvent if necessary and alternately use the razor until the tape is completely off. Clean up any remaining adhesive with more solvent.
Non-solvent, "natural" goo removal methods include using mineral oil or cooking oil. The downside to these alternate methods is if the oil soaks into the wall, paint may not stick to the area without some serious follow-up cleaning.
As an aside, I had one customer with a similar problem to yours. Her son insisted on taping every rock star picture he could find on the walls of his large bedroom. No exaggeration... there were literally hundreds of pieces of tape on the walls! He insisted that, when the time came for action, he could get all the tape off. Needless to say, he couldn't.
In her parental wisdom, she made her son pay for the work... almost 3 hours worth! A little lesson in capitalism and in responsibility!
Thanks for a great alternative to using solvents. Just be sure to get all that grease off before repainting! Of course that begs the question… would you use a solvent to remove the grease??