I tend to revamp their design and flick them a few changes in their backstory/history, making them more complex and reigniting my interest with them. There's no deleting when it comes to my mains, Such as Nomang; she's had six rebirths and has changed into quite the character that I relate to for when I was struggling with my mental health as a young teen. Even when she dies, she'll probably come back again and again.. or be my icon for my future job as a therapist assistant for my business.
But whenever she burns out, and I feel its' her time (when she's older, when the role plays are more focused on the new generation and she's no longer fitting along..) I'll kill her off and play her children, as she leads one of the branches of a big bloodline I'm building out slowly. She'll always be a part of me, though. If I ever am really guilt-ridden, it's for the terrible way I built characters in the past without good individualistic personalities. However, the current rebirth of her is one that washes it all away through her and my past and future struggles.
I've been around since December of 2014 and I am sure to continue role playing, even at the elderly ages if I reach them. It's a part of my life, now.