Use fopen, fgetl, fclose to read your file into a cell array and discard the lines you don't want. Or if you want to write a new file, use fopen, fprintf, fclose and write as your read:
fidi = fopen('somefile.txt', 'rt');
fido = fopen('newfile.txt', 'wt');
tline = fgetl(fidi);
while ischar(tline)
if ~isempty(tline) && tline(1) >= '0' && tline(1) <= '9'
%line to keep
fprintf(fido, '%s\n', tline);
end
tline = fgetl(fidi);
end
fclose(fidi);
fclose(fido);
edit: forgot to read the next line!
