Umm… help 😅

Got these sunflowers a few weeks ago. The one is this pot always seemed to be struggling a bit (my second one has always looked great)

The guy at the flower store that I bought them from said there was basically no way I could overwater them, with how much sun/ warm days we get in our area.
Guess my brain took that as a challenge or something 😅

Whenever they started to look more wilted, I’d water them, and would give a bit extra to this one since it always seemed to be struggling

Well a few days ago I noticed that the water was pooling on the top of the dirt, like not soaking in at all, because it was fully saturated with water.
Turns out that I hadn’t popped out the drainage holes at the bottom of my pot 😅

I googled some quick fixes, which said to drain it (obviously – tons of water came out) and also that I could carefully remove the plant to try to pour the water on top out of the pot, and put in some dry fresh dirt

Anyways I did all that and now they look like this 😅 A few flowers looks like they’re doing excellently, but the rest seem to be slowly dying/ begging to die 😅

I’m thinking I may have damaged some of the roots when removing the plant from the pot to fix the soil, and that’s why only part of it is okay now

I guess my question is – what do I do now? Should I try removing the dying plants? How do I do that without possibly damaging whatever good roots may remain? Do I need to just leave it be and see what happens?
It just makes me kinda sad seeing over half the plant looking so awful – could I cut/ prune off the dying flowers and leaves, or could that potentially harm the healthy part of the plant too?

I’m still a bit of a newbie with gardening stuff 😅 I’d really like if my plants could at least survive a full season, I love them and how they brighten everything up so much!

I’d appreciate any advice y’all have 🤍

Location: South Carolina, USA
Other info- the gardener I bought them from said they would do excellently in the large potted plants on my front porch. I make sure they get plenty of sun. I just failed to realize about the drainage holes and yes I feel very stupid 😞 Thankfully my second pot of sunflowers that I got and planted at the same time have been doing wonderfully. I think they were technically a slightly different species, so I’m a bit curious if that’s how the held up better after almost drowning in the pot 😅 they seemed to absorb the water a lot better at least, even though that pot wasn’t draining either