To unrestrict access to a cell and add more options to choose from, you will need to modify the data validation settings for that cell. Here are the steps to do so:

1. Select the cell that has the data validation restriction.
2. Go to the Data tab in the Excel ribbon.
3. Click on the Data Validation button in the Data Tools group.
4. In the Data Validation dialog box, go to the Settings tab.
5. Under the Allow section, select the option that best fits your needs. For example, if you want to add more options to a drop-down list, select the List option.
6. In the Source field, enter the new options you want to add, separated by commas. Make sure to include any existing options that you want to keep.
7. Click OK to save the changes.

Once you have completed these steps, you should be able to add more options to the cell without any issues. If you continue to encounter problems, double-check that you have entered the new options correctly and that the data validation settings are configured correctly.