Deleting a switch is very restrictive

[Alopalao]

Here are the requirements to delete a switch:

• There should not be installed flows related to switch. This way we make sure no Napps is using switch (of_lldp, coloring, mef_eline).
• The switch should be disabled.
• All tags from switch interfaces should be available.
• The switch should not have links.

Deleting a switch implies removing it from controller. If any service is utilizing this switch, there would be lots of KeyErrors being raised in the kytos console.