Here's a guide to easily choosing which tabs you want to see in the sidebar menu.
In ERP, go to Settings > System > System Module Settings.
You can make edits company-wide by selecting All Company. Or, to make changes to an individual user's view, select that email address.
Next, switch the toggle to "off" next to any menu item you do not need to see.
Once you're done, if you want to duplicate these settings for another user, click Copy Current to another user.
Select a user. Click OK.
When you're done, click Save.
Click Yes.
The user will need to log out and log back in. Once they do, their tab views will be updated.
To hide certain functions from other modules, check out this user guide: How do I add users and set permissions?