Hi aspirant,

No, as per the rules you cannot edit your choice again. Two mock allocations were fone for this purpose only. Now, you can either freeze, float or slide the college allocated to you. 

You might be able to change your choices in spot round of counseling. Below is the link for the list of some of the frequently asked questions related to JOSAA counseling.

https://engineering.careers360.com/articles/josaa-faqs

All the best