Resolved: pick an account + there was an issue with forgetting user@domain.com. please try later

My outlook app on on mobile device was not connecting to my office 365 mailbox as i had recently changed my UserPrinciple name and primarySMTPAddress in office 365, as it was business requirement.

Tried to reset my account but no luck.

Tried to forget my old account but no luck, getting the following error in the outlook app.  

pick an account + there was an issue with forgetting nawaz@olddomain.com, please try later

Tried to add the account with the new smtp address (nawaz@newdomain.com) but no luck, as it again and again asking for the credentials and picking to that old smtp address (nawaz@olddomain.com)

At the end, open the company portal app and found that there was no user signed in. 

so in the company portal app , re-sign in with new PrimarySMTPaddress nawaz@newdomain.com. once the new address verified there, was able to add the office 365 account in the outlook App.