On the web
On the web app, click the Settings icon on your community page > Members
Hover over the member you want to remove and click the trash icon on the right
Click OK

On mobile
Click your profile on the lower-right corner
Click the setting icon > Members
Hover over the member you want to remove and click the trash icon on the right
Click OK

Another way: Click a circle > Click the profile of the member that you want to remove > Tap the vertical ellipsis > Kick from community