In the Settings option of Nelio Content, you can delete a social profile from Nelio Content. Doing so, nobody can schedule new social messages nor any scheduled message will be published on that profile. However, Nelio Content will still have access to that network, since you can have other websites that do have configured that profile and thus need to post messages on it.
To completely delete Nelio Content permissions on Instagram, log in to your Facebook account and click on the Business Integrations option under Settings & privacy » Settings of your account. Facebook will show you the list of apps that have access to your account.
If you click the Remove button to the right of Nelio Content, Nelio Content permissions will be revoked for Instagram and Facebook. If you only want to revoke permissions for your Instagram account but keep them on your Facebook pages, click View and Edit and in the pop-up window disable only the options to access or post on Instagram.
Of course, you can always return to give Nelio Content access Instagram.