In order to change the the App Category Name you have to go through the following steps:
Step 1: From the admin left panel, click on Settings.
Step 2: From the options that open, select App & URLs.
Step 3: Then select Categories from the left side menu bar.
Step 4: The interface that opens will show a list of apps separated by categories.
Step 5: Find the app category you wish to change the name of and click Edit.
Step 6: This will open up a pop up. You can enter the new name in the field under Title.
Step 7: After entering the new name, click save. Your app category name will be successfully changed.