Wow, practically everything you said is wrong, and it illustrates how you really don’t understand how this works.
To answer one of you last questions first:
What law…?
The Controlled Substances Act
And, no, just because Biden has the power to fire the head of the DEA doesn’t mean he has the legal authority to force them to come to a determination he favors. That’s just ridiculous.
The most he can do is what he already did, and that is to direct the HHS to order a review by the FDA and the DEA of the scheduling of cannabis, and they’ve already done that. The FDA has made its recommendation, and now the DEA has to make a recommendation for final approval. That’s the process as laid out by the Controlled Substances Act, a law passed by Congress, which lays out, in very specific detail, the process for this. And no matter what you insist, the president cannot shortcut this process nor force a decision either way.