Depending on how you were added to a Google space, you will either be added to the space automatically, or be invited to join. 

Viewing spaces

If you have been added to a space directly, and not as part of a Google Group, you will be added to the space automatically and it will be listed under Spaces in Google Chat.

You can position the mouse over a space name to show ellipses, which you can click on to hide a space you no longer wish to view in your list.

Group invitations

If you’re invited to a space as part of a Google Group, you will receive an email message which includes a link to join the space. Rather than joining the space immediately, you can preview the space to see if it will be relevant to you: