With app designer you don't need guidata and hobject to store your data.
Create properties in your app and then you can access them from inside any app function using app.propertyname.
For more information read the documentation here
https://www.mathworks.com/help/matlab/creating_guis/share-data-across-callbacks-in-app-designer.html
For example
function f1(app)
% .... %
app.table_name = some_table
% .... %
end
function f2(app)
% .... %
xlswrite('Format.xlsx',app.table_name,'Sheet1','A2');
% .... %
end