Select the cell(s) where you want the dropdown.
Go to the **Data** tab.
Click **Data Validation**.
In **Settings**, choose **List** in **Allow**.
In **Source**:
Type comma-separated values (e.g., `Yes,No,Maybe`), or
Select a range of cells containing the dropdown items, or
Use a named range (e.g., `=MyDropdownList`).
Check **In-cell dropdown** (optional but recommended).
Click **OK**.
To edit the dropdown options:
Select the dropdown cell(s).
Go to **Data** → **Data Validation** → update **Source** → **OK**.
To remove the dropdown:
Select the cell(s).
Go to **Data** → **Data Validation** → **Clear All**.