If you have two accounts you can easily merge them. However, it is only possible if one is linked with a mobile number and another one is linked with email ID:
Request you to follow the below-mentioned steps for merging the accounts:-
1. Login to the email address account.
2. Tap on Account > View and edit profile > edit profile
3. Update the phone number of another account in the email address account.
4. Verify the OTP
5. It will ask to Use Another Phone Or Merge Accounts.
6. Click on Merge Accounts and the account will be merged.
Note: Please note to successfully merge both accounts, either of the accounts mustn't have any active ads on OLX or expired packages.