So I wanted to improve the noexcept of some operators and functions in my code

can I mark this function no except?

std::string remove_suffix(std::string s) 
/*noexcept*/
// is noexcept allowed here?
{
    if(s[s.size()-1] == '0')
       s[0] = 'B';
    else
       s[0] = 'X';
    return s;
}

can i mark this function noexcept and if it happens to throw an exception will it call ‘std::terminate’

I want to make sure of this so I can mark my addition operators for one my classes as noexcept to correct