sweeks

To service this bottom bracket you will need a crank extractor tool which you can use after you remove the bolt in your crank arm. Then you will need a tool like the image below (a "bottom bracket lockring wrench"... the "hook" on the right end) to remove (and eventually re-tighten) the lock ring on the non-drive side; it has notches at intervals around the circumference. You can also use a punch or even (shudder) a screwdriver and a mallet to drive the lock ring off, but you may damage it. Then you can remove the NDS cup and see what is going on in there. If you remove the chain first, you'll be able to remove the drive side crank and chainrings.
If the Bottom bracket hasn't been serviced in 40 years, be prepared to find wear, rust, and who knows what. I just finished re-building the Motobecane whose crank I showed elsewhere. It involved replacing the crank axle and the bearings, but it was worth the effort IMO.

EDIT: Good advice ^^ from revcp. You don't actually have to remove the drive-side cup unless it's in bad shape. Usually the crank axle races are ruined long before the cups. I left my DS cup in place. I also replaced the caged bearings (7 ball per side) with uncaged balls... 11 per side. Better load bearing and longer service life.

BB Lockring wrench