Depending on your permissions, you may be allowed to leave a group. Even though you have left the group the content you posted will still stay accessible by anyone still in the group.
There are 3 ways to leave a Group:
More Tools
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You can leave the group using the More Tools option located on the Group heading.
More Tools option.
Step 1. Make sure you’re in the group you want to remove yourself from.
On the web app:
Step 2. Click on the More Tools option located to the right of the group heading.
Step 3. Click the Leave option.
Leave option.
On a Mobile Device:
Step 2. Long press the Group heading. (press and hold for a few seconds on the heading and the menu will appear.)
Step 3. Tap the Leave option.
Leave option.
Person Info Panel
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You can leave the group using the Person Info panel which will be displayed when you click or tap on your name from inside the group.
Leave this Group option.
Step 1. Make sure you’re in the group you want to remove yourself from.
Step 2. Click or tap on your name or profile image from the Chat list.
Step 3. Click or tap the Leave this Group option.
Group Settings screen
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You can leave the group using the Leave Group option from the Groups Settings screen.
Group Settings option.
Step 1. Make sure you’re in the group you want to remove yourself from.
Step 2. Click or tap the Group Settings option located in the upper-right corner.
Step 3. Click or tap the Leave Group option.
Leave Group option.