Let N be the number of items that is to be removed before and after the locations of the value V in A. (so there are 2*N+1 items to be removed for non-overlapping regions)
A = [10 9 9 999 9 9 11 12 9 9 999 9 999 9 9 13 14]
V = 999
n = 2
% all elements 999 are to be removed, as well as the adjacent two elements before
% and after it (i.e., the 9's in the example array A above)
tf = logical(conv(double(A==V),ones(1,2*n+1),'same'))
A(tf) = []
