What are the spike removal techniques in matlab without using filters
based on your results, you can try a median filter, in Matlab - medfilt1; which takes n-length samples of your series x at a time and computes the median, and apply the median value to each value of x. It is a very common non-linear filtering technique. 

try something like 

result = medfilt1(signal,6)


you and alter the length of evaluation from 6 to whichever number suits the data.