If you have a caste certificate from one state, you can not use it in another state for jobs, applications, admissions etc except for Delhi. This means that you can use your caste certificate made in UP and it  will be valid in Delhi also.

The rule that a person’s SC/ST status will not follow him to another state would not apply to the Union Territory (UT) of Delhi. This judgement was made in 2018 by a five member bench headed by CJ Ranjan Gogoi.

Read more at:

https://economictimes.indiatimes.com/news/politics-and-nation/sc/st-members-from-one-state-cannot-claim-quota-benefit-in-another-unless-caste-notified-there-sc/articleshow/65606738.cms?utm_source=contentofinterest&utm_medium=text&utm_campaign=cppst