I was thinking that driving with what "appear" to be expired plate stickers Is not wise now when leaving the province.

But googling, I can't find anyone advising to now remove all old stickers. Or cover the stickers somehow.

I think just warming them up with "release" the glue holding them up, and hopefully end up with a clean removal. I am going to remove mine as well.

sorry if late for the party,

I used to remove the old one, prior to putting on the new one, as they say to remove, I found just sticking it on is fine... BUT.... what I used to do is below.

I found a chisel, narrow head, just under the sticker, by hand pushed takes it off.

I've done it 3 or 4 times with no problems

I don't have a heatgun, but a hair dryer does not have enough heat and a heatgun could damage the plate. After a year it goes rock hard and is crusty,

yup a narrow chisel used with care will do it, I'm in the GTA and would be happy to give it a try (FOC), you'd need to bring the car over to me though.