2 sided tape, just pull them off. Get yourself an eraser wheel to get the tape off the door. I get them from ATD tools through our paint suppliers. You can chuck them up in a cordless drill and will work good.
I guess I read the original post wrong? Yes the emblems are taped on, and the tape can be easily removed with a drill and an ereser you can fine at most body shop/paint supply stores. I will post a pic of mine soon.
Best way to take them off is with an electric heat gun. They come right off. My buddy bought an 05 with 190k miles (truck is super clean and looks brand new). We just took his off and it makes the truck look so much cleaner. Its here at the shop getting head gaskets, arp head studs, injectors etc. installed so I can snap a pic if you want to see it. Its a must do in my opinion. Thats the first thing I did when I bought my 04 silverado.