Initially on your form in design view, create a button with the button wizard, but select Cancel when the "Command Button Wizard" opens. This leaves you a a button with no code.
To add code to the button:
1. Open the properies window for the button and
a. Give the button an appropriate name, e.g. cmdRunQuery;
b. set the caption property to an appropriate value, e.g. run Query.
2. Then close the property window.
3. Right click the button and select "Build Event," select "Code Builder" in the window that opens, then click ok.
4. Add the following code line
DoCmd.OpenQuery "YourDeleteQueryName" (include quotes)
where YourDeleteQueryName is the delete query you want to run.
5. Close this (Visual Basis) window and open your form in Normal view.
6. Clicking the button with run your query.