Delete Query

I have part of a stored proc that I need help with.
I need to figure out how to delete infro from the
tblManifest using the @ssnDelete variable.
I Have multiple records ffor the given above variable.

Would this need to loop in order to work and that is the solution for this.

I get ther following error when I run the full stored proc.
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Msg 512, Level 16, State 1, Line 2

Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
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Here is the code fro part of the proceedure.
Thanks in advance.

Gene
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CREATE TABLE dbo.tblTempSSN(

ssn varchar(11) null);


OPEN SYMMETRIC KEY SymKeySSN

DECRYPTION BY CERTIFICATE CertSSN;

INSERT INTO tblTempSSN(ssn)

SELECT CONVERT(VARCHAR(11), DecryptByKey(s.SSN)) AS SSN

FROM tblSoldier s, tblManifest m

WHERE CONVERT(VARCHAR(11), DecryptByKey(s.SSN)) = m.ssn

CLOSE SYMMETRIC KEY SymKeySSN;


declare @ssnDelete varchar(11);

set @ssnDelete = (select (m.ssn) as ssn

from tblManifest m, tblTempSSN t

where t.ssn = m.ssn);


delete

from tblManifest

where ssn = '@ssnDelete';



DROP TABLE dbo.tblTempSSN;
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