If you delete a user account and recycle bin is not enabled then download ADrestore from https://docs.microsoft.com/en-us/sysinternals/downloads/adrestore
Open up command prompt and change the directory to were you extracted AD restore.
Run the following command and you will be prompted to say yes or no to restore the user account
ADRestore -r
NOTE
When this restores it restores the AD account as disabled so you need to reset the password first the enable the account.