I'm quite capable of managing this on my own.

Meaning

I can handle this independently.

Examples

• John: Do you need any help with the presentation?
• Alice: No, thanks. <b>I'm quite capable of managing this on my own.</b>
• John: Alright, just let me know if you need anything.
• Alice: I will. <b>I'm quite capable of managing this on my own</b> for now, thanks.