This article explains how to unlink an Instagram account from all devices you have logged in to by resetting your password. This is the only method available to log out of all devices at once.
Steps
Step 1. Open Instagram on your device
The icon depicts a colored camera. It is usually found on the Home screen.
Step 2. Click on the profile icon
It features your profile photo or a human silhouette and is located in the lower right corner of the screen.
Step 3. Press on ☰
This button is located on the page dedicated to your profile, in the upper right corner.
Step 4. Click on Settings
This option is located at the bottom of the screen, next to a gear icon. This will allow you to access the settings menu.
Step 5. Click on Password
It is the first option within the menu titled "Accounts", which you can access from the general settings menu. In this section you can change your password.
Step 6. Type your current password in the first field
Step 7. Type a new password in the two lower boxes
The passwords entered in the two lower boxes must be the same.
Step 8. Click on Save
This button is located in the upper right corner of the screen. This will allow you to disconnect Instagram from all devices you are logged in on.