The Sandbox Accounts page is available in production accounts, at Setup > Company > Sandbox Accounts, It is available to users logged in with the System Administrator role. This page is not available to any other roles. You can use this page to review details about your sandbox accounts and to request refreshes of these accounts.
For more information about the Sandbox Accounts page, see:
Log in to your production account to see the Sandbox Accounts page. This page displays details about all sandbox accounts associated with the production account to which you are logged in.