This is a really bad title, but summarizes what I regularly do and recommend doing regularly.
A nice side effect of using a password manager is, that it gives you a perfect overview about all your accounts. From time to time I go through this list (at the moment I have saved over 200 logins) and see if there are any services I no longer use and need.
If this is the case I go to the website, log in and try to find the settings to delete that account. Sometimes it's not directly possible and I either need to open a support ticket or write an email. GDPR gives me the right to request deletion of my personal data.
But why do I do this?
It's not that uncommon that services get hacked and databases get exposed. By deleting accounts I reduce the amount of data about me that is stored in services databases. This can probably reduce the risk of my data being exposed.
My (current) favorite password manager: Bitwarden.