When you have a retainer you only need to wear it 24/7 for awhile which is usually for only around 6 to 7 weeks.
Then you can switch to only wearing the retainer during the night time.
You should follow your dentists instructions on how long you need to wear the retainer for but you shouldn't need to wear the retainer 24/7 all the time but only for at least 6 weeks.
My dentist told me I could take it out during the day after 6 weeks and sleep with it at night or remove the retainer at night after 6 weeks and only wear it during the day.
I no longer wear my retainer anymore but I did start wearing the retainer only during the day after 6 weeks and my teeth stayed straight.