If you're using the old Acrobat UI, click on Tools - Prepare Form and then on "More" at the right-hand side of the window and then on "Revert to Acrobat Form".
If you're using the new Acrobat UI go to Tools and search for "Prepare Form", then click the "three dots" icon next to "Prepare a Form" on the left-hand panel and then on "Remove e-signing options".
In the future, when creating the form for the first time do not tick the box that says "This document requires signatures", as it converts it to an Adobe Sign form, which has limited functionality.