How to revoke other people's patents

There is no such thing as "applying for cancellation". There is also a "request for invalidation", but it was submitted to the Patent Reexamination Board after authorization. But we need to provide reasons and evidence.

In addition, "similar products" of other companies have been sold "before being authorized". First of all, whether this kind of products are on sale before his application date should be the basis of judgment, not the time node before authorization, that is, is there any evidence to prove that what he applied for was made public before the day he applied? In addition, "similar products" are vague, so it is necessary to compare the specific contents of patent claims in his application with specific products.