The groups you see in Ommnio are all those that the organization considers to be of interest to you.
However, perhaps your situation has changed and there is a group that is no longer relevant to you. If so, you should contact the administrator of your organization in Ommnio (people from Human Resources, or Communication or General Management), as they are the ones who manage the groups and decide who is part of them. They can unsubscribe you from a group from the web version of Ommnio. Pass them this article if they don't know how to do it 👉 How to add or remove a user from a group