Hi Shiva,
You do not need to give log in credentials to a freelancer. There is an option for developers/partners to request access to a store via their partner dashboard: https://help.shopify.com/en/manual/your-account/staff-accounts/collaborator-accounts
With collaborator accounts, you can also limit what the freelancer will be able to access, if you need. I would not advise giving anyone your password, login details, etc.
