When you join an Organization, all of your networks are transferred to the Organization.
Other than that, there is no way to transfer individual networks between accounts.
To change your Organization Owner:
What you can do is change the email address of your account to a different address. From the account page, select “Manage Account” then “Personal Info”. From there you can change the email address.
Note: This email address must not already have a ZeroTier Central account.
Many users prefer to use something like “billing” or “admin” @example.com for their organization owner email account and then invite alice@example.com and bob@example.com as network admins.