Probably best to take them off as the plant will be putting its energy into producing flowers rather than growth.

If they are indoors where you can appreciate them I' d leave them. my 2 are in the conservatory so I like them. If they are in a shed/greenhouse etc then I'd probably take them off. either way you don't want them putting on a lot of growth if they are barely above freezing as the new growth will be 'soft'.

you don't have to take them off unless the buds have opened, by the time the flowers show up roots may have grown anyway.

Flower buds that were planning to appear before you took the cuttings will carry on growing for a while and they can inhibit rooting on some plants, so if your cuttings have rooted you can leave the flowers if you want to, if not I'd remove them -I would remove them anyway but SBG is the botanist here!

i also have lots of geraniums in my balcony, all grown from cuttings and from my experiance its very easy to grow ,plus you dont have to take off the buds,just as long as you have leaves on the cuttings and the stem is quite thick.

I always make sure there are no buds on the cuttings, but any that come later I leave and they seem to be fine.

it is usual to take a non budding stenm for cuttings as the tip/bud produces inhibitory hormones that reduce root formation. The plant will also continue to complete flowering as the hormones involved ensure seed formation etc.