The first thing you should do is change the datatype of the column to
nchar datatypes are intended for data that is more or less fixed length. Your example shows that you are not dealing with fixed length 200 character strings.
Currently each instance of the 'Logged in' string takes 400 bytes. Stored as
nvarchar it will take 20 bytes (and 11 as varchar).
Then you can
RTRIM in an
UPDATE statement to remove the trailing spaces.
NB: In some circumstances you might find that creating a new table from scratch actually works better than the above as the insert can be minimally logged and it doesn't copy the data once and then trim it. It also ensures that no space is consumed by the dropped column. You can use the SSMS table designer to generate the script for this and then add a
RTRIM to the result for something like the below.
SET XACT_ABORT ON;
CREATE TABLE dbo.Tmp_YourTable
YourColumn NVARCHAR(400) NULL
INSERT INTO dbo.Tmp_YourTable WITH (TABLOCKX)
SELECT /*Other columns*/
FROM dbo.YourTable WITH (HOLDLOCK TABLOCKX)
DROP TABLE dbo.YourTable