Take some dental floss or light pound test fishing line. Use a hair dryer and heat up the badge. Place the floss or line behind the badge and slowly in a side to side motion pull the line front to back. Be sure you are pulling the line AWAY and back from the tank not straight back.
A lot of times the badge will pop off. You will have the double sided tape. This is the easiest because all you do is take your fingers and slowly start pushing the tape. It will roll over itself.
Take goo-gone, goof off or WD-40 and remove the residue.