Hello, sorry for the late reply.

You should be able to do so from 

Cesis > Options > Header Settings > Header main area

Then disable the search icon options and save the options :

The pages you imported may be using custom settings, what you need to do to turn off the custom settings is the following :

Go edit the page that has custom settings ( theme panel option not applying to the page )

Then when you are editing the page, scroll down until you see the "Page options" panel.

https://drive.google.com/open?id=1PpZ6XTo-NQVXEnKdP6dQflZqqeU5jWZr

There you will find the same option you have on the Cesis theme panel.

Turn off the "Use custom settings" from the general settings, header, main content tabs, this should fix the problem

Do not hesitate to contact us if you have more questions.

Have a nice day!

Regards.