Hi Lohini thanks for posting in the community - I'm happy to help! Unfortunately at this time changing the persona you selected when initially setting up your account is not possible. However your selection doesn't restrict the templates and shape libraries you have access to. Rather this information allows Lucidchart to suggest resources that might be helpful to someone in your role. 

You should have access to all UML and P&ID shapes and templates that Lucidchart has - I recommend searching the Template Gallery for resources related to these types of diagrams to get started. If you have specific questions about what you're trying to accomplish please let me know and I'd be glad to take a closer look!