How do I 'break up' with someone after 5 dates?

I went out with a guy for 4 dates, ( a date per week) I want to end whatever it is we have going on right now as I feel now that I'm not ready for a relationship with our age gap and maturity levels (he's 6 years older than me) We haven't had sex yet but done everything apart from it at his place. Would it be appropiate to end it by text? or should I go out on a 5th date and tell him then? Any suggestions of what I'll say?
How do I 'break up' with someone after 5 dates?
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