how to delete one word from one filed and add to another filed

I have a title as......> how to get
I have comments as...> peace/happiness of mind
i want the title to be like this...> how to get peace

qtn is how to detach one word from one filed and to attach that to another filed.

I think that your problem requires actually a two-step solution.
a: remove the word - this can be done by a simple search & replace.
b: add the words with a "format field" action: create an action Menu Convert:Action, "new" button
select as action "Format field"
in the definition dialog select field Title
enter as "Format string": %title% %comment%
this will add the comment-field to the title-field

By the way: I Think the forum is full of FAQs about the format field action - so please have a look at these. And sorry also: RTFM applies as well. No insult intended. Perhaps you find other useful examples or dare to experiment a little with the superb functions of MP3Tag