Outstanding tax demand

Go contact the deductor and ask him to file revised TDS returns for the same. And I think as and when the revised returns are filed by the deductor, a rectification request can be made by you. (on logging in to your account) But I doubt if that rectification request can be made online since return was filed offline.

Rectification wont be available online.

Do 1 thing, get TDS return corrected by employer and sit back. You will be in the clear. No worries.

file the rectification u/s 154 on plain paper with proof of ITR and TDS certificate to the AO.

Yes, file rectification petition against the intimation under section 143(1) you have received from your local AO.