What kind of database are you running?
If it's an Oracle Database than you can do a SQL Query on dba_source/all_source and do:
FROM dba_source ds
WHERE ds.TEXT LIKE '%Username%'
For Microsoft Database you would do:
OBJECT_DEFINITION(object_id) LIKE '%Username%'
I had a query that would run through every schema/database on a server looking for this information, because what I was looking for might not be in my database, but I'll have to dig it up if you need more than the above.
The first query I remembered, the second I took from here: https://www.mytecbits.com/microsoft/sql-server/search-find-stored-procedure