readtable does not accept disjoint ranges (e.g. 'A50:A10000,C50:C10000') so you don't have a choice but read the B column as well and discard afterward:
Table_1 = readtable('FileName.xlsx','Sheet','SheetName','Range','A50:C10000');
Table_1(:, 2) = ;
Alternatively, you could use detectImportOptions then modify the import options to remove the columns you don't want:
opts = detectImportOptions('FileName.xlsx','Sheet','SheetName','Range','A50:C10000');
opts.SelectedVariableNames = opts.SelectedVariableNames([1, 3]);
Table_1 = readtable(FileName.xlsx', opts)
Another workaround might be to name the desired range in excel but I can't remember if you can create named disjoint ranges. If it's possible, you could pass the range name to readtable. Of course, this requires the range to be named beforehand in excel, so may not be practical.