I suppose you want to write some data to a specific sheet, here's a sample code you can refer to, which also doesn't creates or adds any new sheet:
% Create a sample table
data = table([1; 2; 3], [4; 5; 6], 'VariableNames', {'Column1', 'Column2'});
% Write the table to a specific sheet in an Excel file
filename = 'testBook.xlsx';
sheet = 'mySheet';
writetable(data, filename, 'Sheet', sheet);
This is what I got:
Hope it helps!
