To create and manage aliases in Google Workspace, follow these steps:

1. Sign in to your Google Workspace admin console using your administrator account.
2. Click on the "Apps" tab.
3. Click on "Google Workspace" and then select "Gmail".
4. Click on "User Settings".
5. Find the user account for which you want to create an alias and click on the user's email address.
6. Scroll down to the "Alias" section and click on "Add Alias".
7. In the "Add Alias" window, enter the desired alias email address. Note that the alias must be unique and not already in use by another user in your organization.
8. Optionally, you can choose to make the alias the user's primary email address or specify a custom "Reply-to" address.
9. Click on "Add Alias" to create the new alias.

To manage existing aliases, simply click on the user's email address in the "User Settings" page, scroll down to the "Alias" section, and click on the alias you want to edit or delete. From there, you can edit the alias settings or click on "Remove Alias" to delete the alias. Note that deleting an alias will permanently remove the email address and any emails associated with it.