I want to edit the "Register Form" with 100 users. Out of 100 users, 98 users will click edit and perform some changes and then click save button remaining 2 users will click the edit button and immediately cancel that page.
JMeter comes with Throughput Controller therefore you can add 2 Throughput Controllers to your Thread Group and in one specify either 98 total executions for "Save form" scenario or use 98% of app virtual users to do so.
Another Throughput Controller will get remaining 2 executions (or 2% of executions)
Check out Running JMeter Samplers with Defined Percentage Probability article for more information on the concept.