The Civil Service Reform Act (CSRA) precludes APA review amongst other relief (since it precludes district court jurisdiction entirely). That being said, this "termination" is likely invalid under the CSRA.

Please see Elgin v. Dept. of Treasury 567 U.S. 1 (2012) for details.

https://www.oyez.org/cases/2011/11-45

https://tile.loc.gov/storage-services/service/ll/usrep/usrep...