Just like you can follow any of the publishers or their Stacks, you can also unfollow them at any time.
To do this:
1. Log into your account and mouse over your profile picture and click Following in the drop down
2. Once you have reached the 'Following' page, click on the grey 'MANAGE' button on the top left, above the publications.
3. Hover your mouse over the green check of the publisher / stack you wish to Unfollow. The green check mark will turn into a red 'X' mark. Click on that mark to no longer follow the publisher/stack. You will see a small red message displaying 'Unfollowed' for about 2 seconds.
NOTE: You will see the green-colored 'Followed' message/red-colored 'Unfollowed' message every time you follow/unfollow a publisher / Stack.
4. Once you've unfollowed that publisher / stack, you should see a 'P' on it, denoting that you have successfully stopped following that publisher or stack.
PLEASE NOTE: You don't have to follow the publisher. You can also just follow one of their stacks, so you won't be bothered with the rest of their stacks cluttering up in your Feed.