MATLAB: How do i remove rows from a column based on the value of a corresponding column

deleting specific rows

I have a large amount of data that i need to process with Matlab but am quite a novice so unfamiliar with all but the basics. I effectively have a large data file containing thousands of entries and i need to know how i can remove a number of specific rows depending on the corresponding value if that makes any sense at all.
Column A is made up of depth values that range from .0000 to 2000.0000m and column B contains salinity values corresponding with each of these depths for a number of stations over a number of years. I want to find if i can remove all values from column B that correspond with values in column A that are less then or equal to 120.0000m.
If(A<=120.0000 then delete B)
I tried to convey this as best as i could in the expression above but don't know where to start with actual equations so any help would be much appreciated.

Best Answer

Assume X is your data matrix,
Xnew = X(X(:,1)>120,:);
So for example:
    X = randi(10,10,2);
    Xnew = X(X(:,1)>6,:);
I'm assuming that by column A you mean the 1st column of the matrix.
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