You can either remove a flow from a solution, or delete the flow from an environment entirely.

Action Result
Remove from this solution The flow is removed from the selected solution, but it remains in the environment. You can use the flow in other solutions in the environment at a later date.
Delete from this environment The flow is deleted; it is not available in the environment.

  1. Sign in to Microsoft Flow, and then select Solutions from the navigation bar.

  2. Select the solution that contains the flow you want to delete.

  3. Select ... (More Commands) for your flow, select Remove, and then select either Remove from this solution or Delete from this environment.

Source: Microsoft