One method would be to use a moving RMS calculation over a small time window. You should know what a reasonable rms value is (based on the characteristic amplitude and frequency of your signal). Use movmean:
movrms = sqrt(movmean(yourvector .^ 2, nWindowLength));
where nWindowLength is the number of elements to include in your window. When movrms crosses some threshold mark it for deletion until it goes back under that threshold. It would probably help to run it through a lowpass filter first.