When you import Asset Store assets, the Unity Package Manager places them in the Assets
directory in your project.
You can remove assets from a project if you know the assets aren’t in use. You might consider this action to unclutter your project directory or to free up space on your local hard drive.
Warning: Make sure your project isn’t using any of the assets you remove.
Make sure you understand these important notes before you begin:
To remove imported assets from your project:
Open your project.
Open the Package Manager window.
Open the Packages dropdown list and select the My Assets context.
Select the package whose assets you want to remove from your project.
Select Remove to open the Remove dialog.
Select the assets to remove. You can remove all assets with All, or you can select a subset of assets by using the checkboxes.
Select Remove.
Important:
If you deleted a subset of assets, you can view a list of the remaining assets by selecting the Imported Assets tab in the Details view.