Is it possible to delete any WHOIS data from owner/admin contact?

It is not possible to delete WHOIS contact information, but you can hide them.
Since 25 May 2018 (GDPR came into force), all WHOIS contact information have been hidden. You might find some data shown below (see pictures) instead of the original data.
The main register sends an email twice a year where they inform you about contact information that they have available and offer an option to update these data. You can update these data through FORPSI.

To change the data in the register you need to issue an authorized ticket. Based on this request we make the changes that ensure domain availability for the future. The main register continuously checks availability of emails and correctness of owner’s address. In case they find any mistakes, they promptly request remediation otherwise they can suspend or delete your domain.

It is advised to react immediately to these emails in case you want to make any changes. If all the data is right, you can ignore the email.
If the contact information in any of the received emails are shown as hidden (Data Protected or Data Disclosed) please answer the email and we will verify the contact details directly in the main registry.