back up, back off, back down (verb)

move backwards from a certain position

"The bully had to back down"

chicken out, back off, pull out, back down, bow out (verb)

remove oneself from an obligation

"He bowed out when he heard how much work was involved"

back down (Verb)

To take a less aggressive position in a conflict than one previously has or has planned to.

Back Down

"Won't Back Down is a song by American hip hop artist Eminem, featuring American pop singer Pink, recorded as the fourth track on his seventh studio album Recovery (2010). It features production from Aftermath Entertainment producer DJ Khalil, who helped write the song along with Eminem, Erik Alcock, and Columbus "Rahki" Smith. Upon the release of Recovery, the song received generally positive reviews from music critics, who praised its aggressive nature and production. Although not released as a single, "Won't Back Down" appeared on four national charts. It was used in the video game Call of Duty: Black Ops and its trailer as well as the trailers for the films Mission: Impossible – Ghost Protocol and Hitman: Agent 47. It was performed on Saturday Night Live and Late Night with Jimmy Fallon.