Those who watch

 In 1978 Congress established the position of Inspector General (IG) in Public Law 94-505.

The President appoints the Inspector General, but the IG REPORTS to Congress.

To prevent political removal or reassigning of an IG, Congress established some guardrails:

Removal Procedure:

The removal procedure for presidentially appointed IGs is found in Title 5, Section 403(b), which reads in part:

"An Inspector General may be removed from office by the President. If an Inspector General is removed
from office or is transferred to another position or location within an establishment, the President shall
communicate in writing the substantive rationale, including detailed and case-specific reasons for any
such removal or transfer to both Houses of Congress (including the appropriate congressional
committees), not later than 30 days before the removal or transfer. Nothing in this subsection shall
prohibit a personnel action otherwise authorized by law, other than transfer or removal."

"The 30-day notice requirement was established under the Inspector General Reform Act of 2008 (P.L. 110-409), and the requirement that notice include a “substantive rationale” was added by the Securing Inspector General Independence Act of 2022 (Title LII, Subtitle A, of P.L. 117-263)."

https://crsreports.congress.gov/product/pdf/IF/IF11546

https://www.congress.gov/110/plaws/publ409/PLAW-110publ409.pdf

Now, what constitutes breaking the law under this act?  Well - not following the procedure!

If the President does not follow this procedure, it could be considered an impeachable act.

It would probably go to the Supreme Court to rule on the original law, but considering that this was not brought up before the action, the "beg forgiveness rather that ask permission" argument I don't think would fly.