Yes. The statute literally leads with "The president may remove the Inspectors General" (quoting/closely paraphrasing from memory). The notification requirement is in addition to this but there's no language which says that the removal power is conditioned on obeying the notification requirement. So Trump legally removed the IGs, and then as a side-effect broke the law by failing to notify Congress.

There's a problem with how the law is written though... It supposedly required Trump to notify Congress before he was even President, but its requirements also only apply to the President. Arguably the law was impossible to follow as written, and I gather that's not even the strongest constitutional problem with the law as written. What we have here is a failure of Congress, and Trump exploiting it.