How to change matrix?

I have a 6*3 matrix and I want to change to 6*2 matrix, how can I do it?

example:

N1=[1 2 3;4 5 6]

then

N1=[1 2;4 5]

Answer 1

[Azzi Abdelmalek]

N1=[1 2 3;4 5 6]
N1=N1(:,1:2)  % : means all lines, and 1:2 means column 1 to 2

Look at Matrix indexing in Matlab