Replace space (" ") with no space ("") in one column
Try this:

To show without space:

select trim(kota) from yourtable


To change your data:

update yourtable set kota = trim(kota);


TRIM function is different to REPLACE. REPLACE substitutes all occurrences of a string; TRIM removes only the spaces at the start and end of your string.

If you want to remove only from the start you can use LTRIM instead. For the end only you can use RTRIM.