Click on Start > Settings > Accounts > Family & other users:
This is where everything happens. You can create new accounts for your siblings, children or any other users in a couple of easy steps.
Add family members
There's a single PC for the whole family? Well, that's not a problem. Each family member can have his own account, even the small ones.
Prior to this operation, you need to make sure that each of the users you want to add have a Microsoft account (firstname.lastname@example.org or email@example.com or firstname.lastname@example.org). A Microsoft account is needed sign-in to Windows 10 and to enjoy all the features offered by the new OS (Skype, OneDrive, Outlook, Sync Settings...).
You can create additional user accounts for the other family members by clicking on + Add a family member. Two choices are available; you can either choose to Add a Child or Add an adult. Make your selection, type the email address of the person in the email field (Microsoft account compulsory) and click on Next:
NB: If the person doesn't possess a Microsoft account, then click on The person I want to add doesn't have an email address and then follow the onscreen instructions to create the Microsoft account.
Type the email address of the person and then click on Next to create the new account. You don't need to register the password, Windows 10 will send an invitation to the selected user. The user can now sign-in to your PC with his own account (email address and password).
Manage family members
Each time you add a family member an entry is created in theYour family list. Select a user account to display additional options:
Change account type: standard user or administrator.
Block: prevent the selected user from signing-in to your PC.
You can customize the settings for child accounts or remove a user account from your PC by signing-in to microsoft.com/family
Add other users
You want other users who are not necessarily part of your family to use your PC? Well, they can have their own account too. Guest users can choose to sign-in with their Microsoft account, phone number or use a local account (username and password).
Click on + Add someone else to this PC, enter the email address or phone number of the user, click on Next and then follow the onscreen instructions.
Create a local account
If you want to use a local account instead, then click on The person I want to add doesn't have an email address:
In the window that opens, simply click on Add a user without a Microsoft account:
Define a Username, Password (optional) and Password hint: