Remove unused codes for IMMS

These unused codes was added by CL[1] and CL[2]
and didn't use now. We should able to safely
remove them.

[1]: I4dc9d6513d0559156f7da39244f3fc5ebc952ed4
[2]: I7df18b095d33ecafffced75aba9e4f4693b0c393

Bug: 236920321
Test: presubmit
Change-Id: I044f409aa521b77f5689b8650785211becc2f450