What power can congress use to stop a president from performing executive functions?

The answer is removal power. Congress can use removal power to stop a president from performing executive functions.

The correct answer to this open question is the following.

The power Congress can use to stop a president from performing executive functions is the Removal Power.

US Congress has the power to impeach the President of the United States and remove it. If Congress considers that the President broke the law or is accused of treason, Congress has the power to remove it. For instance, that was the case of the Watergate scandal, when Congress impeached President Nixon and he resigned. Bill Clinton was also impeached by Congress due to the Monica Lewinsky affair.

it affected it because the kingdoms (with trade) slowly got richer and richer.