How to move a unique_ptr?

I have this code:

unique_ptr<int[]> p1, fitness_data (new int[NewPerson->num_entries]);

...add data to fitness_data...

p1 = std::move(fitness_data); //Attempt 1 or...
p1(std::move(fitness_data)); //Attempt 2. Either attempt is commented. 

Both stop the program with exit code 139. My IDE, CLion gives the error

'unique_ptr::operator=(const unique_ptr &)' is deleted

I'm assuming that the error is referring to an attempt made to copy the pointer, But I need to move it.

I would appreciate any help. I would hate to have to move back to manually freeing memory again. Unfortunately, the version of OpenMP we are allowed to use does not get along with vectors.

Thanks, Daniel