Dick has left his Robin identity behind before, as in Tales of the Teen Titans #44 (July, 1984, by Marv Wolfman and George Perez)...but how about just becoming an adult and staying Robin?
Justice For Robin
But, this was the end of Robin's "Bat-costume"...
Robin Grows Up On His Own
Robin started to sport an "adult" Robin costume as of All-Star Comics #58 (January-February, 1976, by Gerry Conway and Ric Estrada, and a cover by Mike Grell, also the first appearance of Power Girl!).
That costume should look familiar...it was the one the Earth-2 (JSA) Robin gave to the Earth-1 (Teen Titan) Robin in Justice League of America #92 (September, 1971, in a story by Mike Friedrich and art by Dick Dillin, but the costume was designed by Neal Adams, it even said so in the comic!).
...before a starring role with the Earth-1 Batman in Brave & the Bold #182 (January, 1982), then back to the back-seat for Infinity, Inc. #1-6, 8 and 9, America vs. the Justice Society #1-4, Infinity, Inc. #21, Infinity, Inc. Annual #1, and Crisis On Infinite Earths #5, 10-12, after which, we saw him no more. Still...the original Robin lives on in our hearts!
And, the majority of these appearances have been collected for you to enjoy!