If you import the data as a table, I don't think you are allowed to have a 'blank values'.
Consider a following example:
clear all;
clc;
t = readtable('example.xlsx');
The output will be:
It is possible to 'blank' the cell when you turn the Table in into Cell array:
clear all;
clc;
t = readtable('example.xlsx');
tC = table2cell(t);
tC{3,1} = [];
xlswrite('example1.xlsx', tC);