How Do I Clear All The Things From The Canvas?

After clearing all symmetrical shapes from the Canvas, when I choose again any symmetrical shape on Canvas, it shows me removed symmetrical shapes also. What can I do that it that it cannot show the removed symmetrical shapes after choosing the new symmetrical shape?
Please Help Me In This.

Please tell me that what is the problem in asking this question.

what's this? how did did you remove it? how to choose it?