First, use readtable instead of xlsread. It will automatically detect that the first row is a header and use that to name the variables of the table. This will simplify the code for obtaining the title column to just:
alldata = readtable('Data.xlsx');
CMA = alldata.title;
Now if that title column is a cell array of numbers and text, then
CMA = str2double(alldata.title);
is probably what you're after. If not, attach an example file so we understand exactly what the input is.
You could also try
alldata = convertvars(alldata, 'title', 'double');
to keep it all in the table.