Hi @Mark Sanchez ,
The best practice is to add the new form of encryption before removing the old form of encryption.
CLOSE SYMMETRIC KEY SymKey1, you also need
DROP SYMMETRIC KEY SymKey1
Then follow the steps in this blog: Using Asymmetric Keys to Implement Column Encryption
However, One thing to note is that RSA_1024 and RSA_512 are deprecated. To use RSA_1024 or RSA_512 (not recommended) you must set the database to database compatibility level 120 or lower.
Here is a related official document: CREATE ASYMMETRIC KEY (Transact-SQL)
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