Green’s Dictionary of Slang

to withdraw, to give up.

2009		A. Kleinzahler Music I-LXXIV 212: [W]hen Wexler turned up with his bucket of cash, Jim and Estelle were more than ready to cash out.
2019		V.D. Hanson Case for Trump 159: When Trump of all people could deal the stronger moral card, then his opponents would be wise to cash out.