Hello, teachers and colleagues.
i'm analyzing Owncloud core codes
question..
is this the right place to question about code?
lib\public\Constants.php
If you look at the file, you will see a deprecated const variable but why not erase it from the code if it is not used?
This is my curiosity as a young developer.
1) Yes, it is the right place for questions about the code. Welcome to the community.
2) I have no answer to this question, IMHO, probably they are just forgotten. You are welcome to make a pull request to remove them. In this way, core developers review your pull request and you can get your exact answer. Win-win for both sides 
These can only be removed once all occurrences of \OCP::PERMISSION_XXX have been replaced everywhere in the code.
If you do submit a pull request, please check whether some of those occurrences still exist and adjust accordingly.
Since this is old from OC 8.0.0, we can assume that most apps are not using these any more.
Dear karakayasemi
I'm a jonior developer. So i didn't think my idea was the answer.
And pull request thought what I could do after I thoroughly analyzed this code.
But when you immediately put in a pull request and asked for an aswer, it was fascinating.
I think I will be very funny.
Thank you for your answer.
Dear Pvince81
I judged the situation by the word the "deprecated"
I thought it was a verified annotation. But when I sent the Pull request I knew I had to check them out again.
I think I have more to do list. Thank you for your answer.