Try the following:
DECLARE @t TABLE (StartDate DATETIME)
INSERT INTO @t VALUES (CURRENT_TIMESTAMP), (DATEADD(QUARTER, -2, CURRENT_TIMESTAMP))
DECLARE @Col Nvarchar(Max)= ''
Select @Col +=Quotename(CAST(Datepart(Year, CAST([STARTDATE] AS DATE)) AS NVARCHAR(10)) + ' - Q' +
CAST(Datepart(Quarter, CAST([STARTDATE] AS DATE)) AS NVARCHAR(10))) + ',' FROM @t;
SET @Col = LEFT(@Col, NULLIF(LEN(@Col),0) - 1);
SELECT @col