What should I do with these units?

In my opinion, you shouldn't merge a unit unless you plan on getting them to a higher merge than, for example, +1 or +2. I'd keep one for Cancel Affinity fodder considering my F2P status.

It's different with units like 4* Cherche considering she's pretty common to get when doing mass rolls for green units, or units like Nowi since she's pretty easily obtained at 4*s. Innes, on the other hand, is 5* exclusive and the banner that has his focus is about to end in a few hours.

As far as Bridal Charlotte, I'd keep her. Only skills I can think of getting from her as far as fodder is Wind Boost 3 (not everyone uses these skills, but can be useful depending on team) and Threaten Attack 3. So it's really up to you. -Atk Charlotte can use a Atk +3 Seal to bring her bane to a neutral Attack stat, so it's up to you as far as what to do with her.

You can always save her in case you roll another Charlotte and merge them? Again, it's up to you. lol

I got a bridal charlotte a while ago (different IVs, but still) and regardless I recommend using her. Her attack stat is pretty high, and since she has so much HP, wind boost is kinda useful on her and can help with your speed bane. At least with a res boon she wont get one shotted by some common mages, and like the above said, you could always just put speed +3 has a sacred seal. As for your Innes, your +spe one is perfect for a Brave build if you don't already have one. May as well keep the other one around, you never know what the new meta may be, and his skill is 5 star exclusive I believe? So it may come in handy later.