Appendages (detachable) – The ability to detach appendages and/or parts of your body. Arm-Fall-Off-Boy (DC) has this power.
Captain Marvel (M. F. Enterprises) also has this power.
The power is clearly a useless one in the case of Arm-Fall-Off-Boy and therefore not really a power but Captain Marvel’s appendages are self-propelled and this version is clearly a power.
In Adventure Comics V1 #350, Colossal Boy (DC) uses psychology to defeat the formidable the Jigsaw Creature.
Jigsaw (Dakotaverse) was blown up but the pieces of his body can still operate independently (Milestone Media Universe Card Set).
Rockslide (Marvel) can detaches his stone arms in New X-Men: Hellions #1.