Campaign! 

There are basically two ways to vote an officer out of office.  State nonprofit corporation laws usually permit removal of an officer whenever the board believes it is in the best interests of the corporation.  The more genteel way to get rid of an officer is simply to nominate someone else for the job at the next election.  In either case, it depends on the votes of the people voting.

If you want to keep the office and think some of the directors are plotting against you, talk to the more neutral directors about keeping your position and perhaps finding out why the plotters may be against you.  You can also talk with those who want you gone to see if you can convince them why you should be allowed another term.  When you are in an elective office, it really helps to find out what your constituents want and to figure out if and how you can satisfy their wants.  If you have members who vote on officers or directors, you may need to campaign with them as the ultimate electors.

Many nonprofits are delighted to have someone who is willing to take the responsibility of being president.  But where there are contested elections, it can be politics at a very local level.