I read the documentation about verifying domains in Amazon SES, and I don't understand - how long does the domain verification last and does it expire?
What happens if I remove the DNS settings after I verified a domain? I tried to do it with the DKIM DNS settings, and there I received a notification that the DKIM of the domain would be revoked, unless I restored them. But with the domain itself, I removed the DNS settings and I didn't receive any notification.
Based on this information, you should leave the TXT record in place: Creating and verifying identities in Amazon SES:
Else, after the next check by AWS, they will revoke the verification. They will warn you about the pending revocation though and give you 72 hours to react.
--Edit--
Unfortunately the original Answer has been removed from the linked AWS resource. Another site referencing the same original resource can be found here: Removing Domain Verification Record after verification in SES