The electors of a parish cannot force any councillor to resign. If pressure does not work, then the only thing to do is wait until the next periodic election comes round - which will be in 2015.
What you can do is to hold a parish meeting. One should be held annually, but one can be convened by any six electors. A parish meeting can discuss anything to do with the parish, and can vote on resolutions. However, resolutions that are passed are not binding on the parish council - but they may give a clear indication of local feeling.
More often than not, councillors will eventually back down when faced with concerted pressure from electors - but it can be a struggle!