Admin can set Variation discount on the product variation.

For making this discount rule select Discount Rules tab.
Now choose Variation Rules.
Now click on Add New Rule .

Make rule according to your choice.
Fill Rule, Restrictions and Validity tabs accordingly.
This rule can be shown in the table and also it can be editable.

Now you have to give permission to your rule to give discount on the product you have chosen.
Click on the Setting Tab.
Check Variation Rule as shown below.

After checking these rules, Choose among First Match Rule, Best Match Rule or All Match Rule and click on save rule button below.

Now select the rule which you want to apply on edit product page as shown in the figure below.

The discount can be shown in the cart if the products are added to the cart as in the given picture below.

Now whenever you want to disable this discount rule, you don’t have to delete it, just go to Setting Tab and uncheck this rule.