What are the Effects of Deleting a Requirement

You can delete requirements in the following ways:

Deleting a requirement from the Requirements list page deletes the requirement permanently regardless of any associations with products, releases, features, sources, or personas.
Deleting a requirement from a product, release, or feature does not remove the requirement permanently.
If the product is the last product association for the requirement, you cannot delete the requirement from the product.
Deleting a requirement from a release or feature does not delete the requirement from the associated product.