Using POST request for deleting and getting data

How bad is to use POST operation for deleting entity or getting entity?

In my context I'm creating api, where is request with device MAC address and username. The request deletes the device from the user.

Next request requires device MAC address, and secret key to get data about the device.

I want to have this requests secure and dont want to show arguments in request address, because this data are quite private, so I want to use POST operation.

Is it very bad, only bed, normal, ok, good solution...? Thank you.