As some know and some have discussed here, the twenty-fifth amendment does provide a mechanism for removal of a President, who is unable to meet the demands of the office.
Twenty-fifth Amendment to the United States Constitution
Section 4.
Whenever the Vice President and a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide, transmit to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office, the Vice President shall immediately assume the powers and duties of the office as Acting President.
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This google search will take you to your preferred source for the complete amendment and the complete Section 4. If the President requests to resume power, and the Vice President et al disagree, the matter must be decided by a 2/3 vote in Congress.
There have been unusual concerns about the current presidential office holder, both here at this website, and in the nation at large.
Please take a second to answer the poll below about whether it is time to talk seriously about the use of Section 4 of the Twenty-Fifth amendment (25/4).