I tried many things but best way to wither-off these unwanted portions is to use threshold. here i'm taking 20% as threshold value. As i have both positive and negative sides, hence i used "b = find(amp1<a & amp1>a1);"
if true
a = max(amp1);
a = 0.2*a;
a1 = -1*a;
b = find(amp1<a & amp1>a1);
amp1(b) = 0;
amp1=(amp1(amp1~=0));
end