Hi Quoc,
How to change this clause in/into subordinate clause?
You can't make a correct question in this way. You need to say something like
How do I change this clause into a subordinate clause?
How do you change this clause into a subordinate clause?
How should this clause be changed into a subordinate clause?
In addition, the pronoun 'one' should replece the second word 'clause' in each of these examples.
Best wishes, Clive