KanjiJLPT N1
Retract

remove, withdraw, disarm, dismantle, reject, exclude

Mnemonic

You used your hand to bring up a ninja from the underground for a secret mission. But plans changed — now you must retract him! You grab the ninja by the arm and shove him back down the hole before anyone notices he was ever there.
Additional thoughts
Visualize your hand reaching into a trapdoor, pulling up a ninja, then frantically stuffing him back in. The urgency of undoing what you just did reinforces the meaning of retract.
Quick recall
A hand that bring ups a ninja must retract him when the mission is scrapped.

Details

The keyword for 撤 is retract. This kanji conveys the idea of pulling back, withdrawing, or removing something that was previously put in place. It is commonly associated with actions like retracting a statement, withdrawing troops, or removing equipment from a location. The sense is one of deliberately undoing a prior action or position by pulling it back.
On'yomi
てつ