How to make a Delivery Date as a required field?

1. Go to account settings. To do that click on the account icon in the top right corner and choose Settings from a dropdown menu as shown below:

2. On the left side menu find the Custom Fields tab and click on it:

3. On the opened page select PO Custom Fields and click the Edit button next to it:

5. The settings for the following fields are displayed. Click the toggle Required to switch it on:

6. Save the changes