How to delete ".exe" for my filename?

Question

Hello! I wrote an application that can open and get the filename from a specified location, but I would like to get the filename only for my inputted textbox. It display "demo.exe", but what I want to display on the textbox is "demo" only. So how to delete the ".exe" on the textbox? e.g. textbox1.Text=filename; The textbox1.Text will display demo only, but not demo.exe? Please give me reply asap. Thx.