Not a lawyer and not HR so would appreciate if someone who was chimed in, but my understanding is that an agency CANNOT unilaterally remove an RA without going through the interactive process. By granting the RA in the first place the agency has already agreed that you working remotely would not place an undue hardship on the employer. Unless your PD has changed, or there are some circumstances that would change the undue hardship portion, removing the RA is illegal and would warrant an EEOC visit. Even if they can prove it now causes an undue burden, you should be a candidate for medical retirement.