Having a Nintendo Network ID and Local User profile on the Switch will enable the console to store your saved game data, achievements, screenshots and video to the cloud as well as remember your preferences.
What you need before you start:
The Nintendo Switch should be connected to a reliable Internet connection.
2. Create Nintendo Network ID
Select System Settings.
Scroll down to Users.
Select the User.
Select Link Nintendo Account.
Select Create Account.
On your PC or smart device, visit http://accounts.nintendo.com and create a Nintendo Account.
Once you have created the Nintendo Account, return to the Nintendo Switch and click Sign In.
Sign in using the information for your Nintendo Account.
3. Create New User
Select SystemSettings.
Select Users.
Select AddUser.
Set your Icon.
Select a Background Color.
Enter a nickname.
From here you can sign in and link your Nintendo Network ID or skip the process.
4. Delete User Profile
Select System Settings.
Select Users.
Select the User Account you want to delete.
Select DeleteUser.
Check the box next to Delete.
Tap Delete This User.
Tap OK once the account is deleted.
5. Create a Child's Account
If you already have a Nintendo Account
Sign In to your Nintendo Account at http://accounts.nintendo.com.
Select Parental Controls.
Select Create an account for a child.
Next, enter information for the child who will use the account.
After confirming the content, select OK.
If you do not already have a Nintendo Account
Visit the http://accounts.nintendo.com.
Select Create a Nintendo Account and follow the instructions on screen.
After creating the parent or guardian's Nintendo Account, follow the instructions above to create a child account.