from my main cast I deleted three characters. for now.
in case of the first one, I realized I was getting more and more tired with writing her. every scene she appeared in I didn't know how to write dialogue for her or understand what she wanted. yes, I did define her personality, motivations and goals, but I just needed time to understand that she was slowing down the plot, not pushing it forward.
and with the other two, I dreaded this moment. I loved their dynamic with my whole heart, so when the thought of scrapping them popped into my mind I immediately rejected it. but then I dug deeper into their story and what they bring to the plot. and then instead of "but I love them so much how can I even think of them not being" I thought "yeah I'll delete them". and instead of guilt and panic I felt relief.
but at the same time they had some qualities that I didn't want to get rid of completely. as I said, I loved the dynamic of my duo, the carelesness of hers and the gentleness of his, so I modified some characters and gave some of their personality traits to my existing heroes so as not to lose them. I can say that I incorporated that two characters into the remaining of the main cast, and gave their dynamic to the other couple.
as for my first one, I kept her. but as a character that appears only in the epilogue. she's still important to one person in the main cast so I couldn't just erase her completely. the mains are doing well without her. and she still has an emotional impact on the story. I just moved her to a better place and time.
I see that you already figured that out, but if anyone's still struggling to delete a character, this is some of my advice I can give: define what qualities, relationships, or impact on the plot you want to keep in your story, and then determine if you need a whole separate person to carry it all. as I stated earlier, if you can move some of them to another character, then deleting is probably the better decision. and if you really want to keep the character, make them less important, or at least not part of the main cast, so they won't take as much of your time and words writing and developing them. and when you decide to delete them, that feeling of relief is the best sign of making the right choice.