Thank you all for your answers , you were right , there was no need export the file.
For those curious why i had to do all these conversions: The reason is that initially i create a design in canva (this is a web app). Then i download the file (which is rgb) from canva and import it in photoshop.
This file is purposed to be print and the company which will print it has adviced me to work in cmyk then make it rgb and sent it to them. So since the file imported from canva is rgb , i change it to cmyk i work with it and then i change it to rgb to sent it to the printing company.
Thank you for your time reading and answering my question.
Regards,
Nik.