As we discussed on the way to the Stumble, I have a similarly-aged Motobecane. Bought it circa June 1974, when my totally unreliable Renault (automobile) induced me into bike commuting (Arlington to Acton). A lot of miles in those first couple of years, not many since. Last rode it maybe mid 80s.
Now we're cleaning out the garage and it's in the way. But I have a hard time parting with things. (I blame that on my mom.) So I have to come up with psychological tricks. So here's my trick for getting rid of the bike:
Take it to a local bike shop. (Back in the day I did all my own bike, and car, mechanicking but no interest in that now.) Ask them what it would take to get it back into working order. Expecting one of two outcomes.
1% chance: "Sure, we can find the parts, and the labor won't run you more than double a new bike." Then I have a vehicle for the cross-training I've been meaning to do, and a bike is a great way to enable long one-way trail runs and hikes with only one car (just hide the bike in the woods near the finish).
99%: "Ha ha ha! Very funny! Probably impossible, or ten times the price of a new bike. Or there's a $25 dump disposal fee for bikes." Which would make room in my side of the garage. (Betsy's been parking in the garage during snowstorms but I haven't been able to, thanks to my "stuff").
What kind of shape was yours in and how much work/money was it to revive it? Mine is pretty sad right now after decades of neglect, several years of outside storage, etc.
So far I've replaced the tires/tubes/rim tape, and I oiled the chain. I'll probably also replace all of the cables and housings, but that may be with NOS left over from my father's stockpile (which my brother has).
This will be filling in the "utility bike" space in my collection. I have a pretty good mountain bike, a suitable road bike (one of my brother's old racing bikes), plus my recumbent and unicycle. None of those are appropriate for the sort of one-way retrieve that you mention for trail runs and kayak trips. I used to use my old mountain bike (with slick tires) for that, but I gave it to my niece for use as a campus cruiser.
That still leaves me with no fat bike. I've considered it, but do I really need another bike?
Getting rid of a bike is easy, they'll usually take them at electronics recycling day, you might need to pay $5. And they usually fix them up and send them off to charities in third-world countries. Or just google "donate bicycle".
I dropped a Claude Butler bike I got in England in 1970 at our recycling center. I had had it converted 5 to 10 speed to be ready for something, not sure what. Butler had been a big racing star back then apparently. I rode around London a bit but not as much as expected. Used it here for a while until the riding group convinced me to upgrade. Still worked fine.
Bikes left there were repaired by a local retiree who donated them to needy. I have seen it a couple times at our library. Not sure who has it but still looks good. So there are paths to donations that are useful.
We donated our late-70s Motobecane 21-speed bikes, not ridden in a number of years, when we moved several years ago. There is/was a bike charity group that restores them and donates them to the needy in Troy, NY.