There are multiple ways to deactivate a form. Each is explained here.
1) Move to the 'Archived Forms Folder' - You can archive the form by moving it to the 'Archived Forms' Folder of your account. This will automatically deactivate the form and will display the following error message if someone tries to access it from the Publish link or embedded form:
This form has been deactivated and is closed to any further submissions.
2) Disable Now - You can archive the form by changing the 'Disable Form' setting to 'Now' in the form's General Settings page. This will move the form to the 'Archived Forms' Folder automatically and the same error message will display to the published form viewer as above, but this option does offer the ability to change the message that is displayed.
3) Disable 'On Date' or 'After Number of Submissions' - This method will cause the form to deactivate at a specific date and time or after a specified number of submissions. When this happens the form WILL NOT be moved to the 'Archived Forms' folder. Instead, the form will 'Expire' and will stay in the folder it is currently in, but will display a red badge next to the form name.
The default error message will still be displayed (unless edited from the form's 'Settings' page).
This option is ideal for instances where users only have access to a particular folder on the account. When a form is archived using the options 1 or 2, the form will move out of the folder and will no longer be accessible to the user.
Note: All deactivated forms, whether archived or expired, count toward your account's form allowance set by the Form Plan.
Reactivating Archived Forms
To reactivate an Archived Form go to the Forms menu > 'Archived Forms' Folder > Place a checkmark to the left of the Form(s) > Click the Restore option along the top of the page.
To reactivate an Expired Form click on the form's 'Settings' tab > Change 'Disable Form' to 'Never'.