Remove "Oops! That page can’t be found."

Can you tell me please if it is possible to remove "Oops! That page can’t be found."

I tried changing it using Ultimate Branding but because of the apostrophe the text to replace is Oops! That page can’t be found. but it keeps reverting to the apostrophe and then it is not recognized. I think the best thing is just to remove it completely.

Thank you.