Welcome to the Asana Community Forum @Deepanshi_Bansal 
Great to hear that you moved to Asana for project management 
In regards to your question I am not aware that this can be hidden or removed.
All in all Asana is trying to display all available features.
If you are not ready yet using them maybe create a dummy team goal and name it so your team members know it should not be used yet.
Or better instead try to move all over to Asana already? Might be easier to avoid switching tools and help your team with the adoption of Asana for all their processes and workflow if they can achieve all within one tool.
Plus if you do not have the goals in Asana you won‘t be able to connect projects and tasks with them meaning you cannot utilize the cool automated goal updates and more which improved efficiency.
I wrote a post about this recently, have a look here.