I have completed my degree in Telangana state but I want to study pg in Delhi ,what can I do
Since, you have already completed your undergraduate course in Telengana, you can surely apply for other post graduate courses in Delhi.
You can apply to your choice of college with your choice of subject from its official website. They may have some entrance examination or can provide admissions based on some national level exams. This will depend on the pg course you are willing to pursue.
I hope this helps you !