Rules for removal of chairman from committee

Our society has elected managing committee of members in August 2010. Now, due to disputes and other problems, five committee members want to remove the chairman. They are also demanding re-election of the entire committee or they will resign and reduce committee to minority. Will our committee be valid then? Tenure of our committee is 5 years which is found to be quite long.
In the context of your query, chairman, secretary or treasurer can be removed by a no-confidence motion in a special meeting of the committee called and presided by the Registrar or under delegated authority by an assistant registrar or an officer above his rank. 
The notice for such meeting will have to be given by one-third members of the committee and motion of no confidence is to be passed by three-fourth members present at such meeting. Attendance at such meeting will have to be two-third of the committee members. 
If 5 out of 9 members of the committee resign, the strength of the committee would reduce to minority and apparently, functioning of the committee becomes questionable. However, the apprehensions about the validity of the committee are ill conceived. It is true that to transact business at a committee meeting, members present should form quorum agenda. However, such requirement of quorum would not be applicable for the purposes of filling in vacancies caused by death, resignation, disqualification or removal of committee members. Period of office of a co-opted member, would be co-terminus with tenure of the committee, which in your case is 5 years from the date of election. Tenure of the committee can be reduced by an amendment to the byelaws