How to hide this white orchid?

Patryk,

This someone also removed the petal of the yellow one that is partially hidden behind the white one, along with the faint parts at the bottom; and then the background of the yellow one is basically empty, with only a bit of colour transition.

Withot that it would never look right.

Apart from removing the unwanted bits in Photoshop, you can also:

1) Draw along the yellow petal with the Pen Tool;

2) Continue to close the path in a simple way to include all the unwanted parts;

3) Use the new path as an Opacity Mask, you can give it a black fill (no stroke) and leave both Clip and Invert Mask unticked;

4) Apply a background path with a colouring that matches the remaning parts of the image.

You may consider whether you will be satisfied with the resulting stretched image, if you also intend to stretch yours. You can start by stretching as is and see.

You want to use Photoshop for that, not Illustrator.

Pick up a color from the surroundings.

Or maybe try the healing brush or AI features to hide it.