Pulldown Tab -- Extraneous

Using a Workbook derived over many versions created long ago by others
When I enter certain columns to enter data in a cell, a Pulldown Tab automatically appears.
- clicking on the Tab, nothing "pullsdown"
- suspect this is remnant of a former pulldown listing of values allowed in the given column

Two related questions:
(1) How do I get rid of these extraneous tabs/buttons?
(2) Where do I go to create my own pulldown tabs listing legal values for a field.

Thank you.

Be safe. Be well. Let's get vaccinated when it is our turn.

Dennis Galon