As a sysadmin/tenant admin you cannot delete users, but you can block users, which has similar meaning as explained from most perspectives.
Once a user is blocked on Qmarkets system he cannot access the system, his data is saved for your company internal analytical purposes.
If you wish to remove the users personal data (name, email, etc..) you have the option to anonymize users.
Anonymizing a blocked user allows you to keep all information regarding his ideas and input on the system but protect his privacy in aligned with the GDPR regulation.
For elaborated step by step introductions on how to anonymize please see the User Anonymization and Privacy article