A:
There is often confusion about the word "impeachment."
Although it means "the accusation and prosecution of a person for treason or other high crime before a competent tribunal," many people misunderstand it to mean "removal from office."
A recent example is the impeachment of President Clinton who, however, was not removed from office.
If your question is asking about the removal of your president from office, there's much more to it than just voting.
In particular, he is entitled to a trial and fair treatment.
This question is so very important, and the answer is so complicated, that to do justice to your president and to your organization, I strongly suggest you read Section 60 of RONR, especially the part beginning on page 644.
Does the accused vote about his own removal from office?
No.
After the trial, he is removed from the meeting room while the assembly votes.
He is brought back in afterward to receive the result.