Reading the manual for the PRIV I see standard WIFI options that allow the phone to connect to previously saved networks. Unless your home unit is weak or the channel it is using ( which can be changed) is also used by close WIFI routers such as neighbors you will get some level of interference. I had to change my own due to a neighbor adding multiple sub units with the same channel I was on with my router.
As for the ability to drop saved networks. this link for the phone shows how.
which I'm sure you already have.
You can also option the phone to not connect to WIFI when traveling.
Wi-Fi frequency band Tap to set the frequency band. When you set the band to 5.0 GHz, your device
connects to access points on the 5.0-GHz band only. When set to 2.4 GHz, your
device connects to access points on the 2.4-GHz band only. When set to
automatic, your device tries to connect to the band with the stronger signal