Hello.. I have a locked rear right wheel. I think it's due to the fact that the safety brake was was engaged during the winter. If it is the brake..how can I unlock it?

1. verify if the caliper itself is seized forcing pads against the rotor. you would know this quickly by driving the car a few miles and feeling the wheel for excess heat. you'll know it fast if its seized

2.if the caliper is good remove the wheel only because it makes access easier ans look behind the rotor for the rusty e brake spreader which cable connected and opens and closes slightly to activate the e brakes. once found spray liberally with p blaster or something like it and work the e brake handle up and down while slowly driving around the block. the friction and vibration of motion on the ebrake is better than just sitting stationary and doing this.

3. if none of the above works you have to remove the caliper hang it out of the way and use an 8" 3 jaw puller to remove the rotor or you might be banging on it for quite a while making a mess. then you can gain access to the spreader and do what needs doing

this is what you're looking for

https://www.eeuroparts.com/Parts/31226/Parking-Brake-Expander-Arm-1205849/

worst case you have to remove and loosen it up on the bench

Maybe you can remove the rear wheel and try prying the pads away from the disc. or unbolt the caliper and try knocking it back and off with judicious blows of a hammer?

Wiser enthusiasts, please correct me...

Thanks. By the time I loosened the second nut that secures the wheel- the wheel started turning. It has just been siiting for a while.

Keep an eye on that wheel!

Use can your sniffer while passing bye back there after driving the car for some distance.
If the pads out gas you will know it's too warm.

The right rear caliper are notorious for being the first to stick on these cars. I have read quite a few post like this.

It just speculation on my part that it's the farthest caliper away in the whole system and the coolest. Moisture will travel there and cause problems first. It's physics at work.
The front calipers get more heat naturally cause they do more work and the MC is under the hood with an engine in most cases.
I have noticed over many years that rear engine cars seem to get more MC replacements along with rear drum brake cylinders getting leaky or stuck.

It just my observations between designs that have some linkage I guess?
Change out the fluid on regular basis. It's up to every three years with some fluids but I exchange the fluid in the reservoir more often. It's only a few ounces and it keeps my stock of brake fluid turning over.
My idea is the fresh fluid absorbs back moisture towards the reservoir since it has an affinity to attract moisture. I use it against itself.

It's aways good to walk on the "far side" and short cut surprises.
It can also make you feel like you are the "Captain" of a low flying vehicle. (:-)

Phil