@Akathma this is a sort of thing a member of customer support would be able to assist you to quit or cancel a historical sync. Please follow the guidelines here on how to contact support: https://help.klaviyo.com/hc/en-us/articles/115001002272-How-to-Contact-Support

Sure. Thank you. 
One more quick question. 

Suppose the account has 10000 profiles but the payment is done for 5000 profiles. Can we run the account for 5000 contacts? 

@Akathma unfortunately this capability is not possible at this time.  If historical sync was not run, we could only control the date range for orders to sync assuming you would have periodic sync that will keep running for the duration of the integration to keep synching recent data.  We cannot set controls on the amount of contacts synched by the integration.

@klaviyojad 

1. When we integrate woocommerce and Klaviyo - new data will be automatically synced. Or do I need to go there periodically and re-import to sync the new data?
2. With the help of support I will be able to sync only certain historic data or completely stop historic sync. I can’t do it through the plugin in anyway myself?

@Akathma when you save the Integration Settings Form in Klaviyo it starts the one-time historical sync and sets jobs that run hourly to sync data.

With the help of support you can halt the historical sync and keep the other syncs still running.  Its not something you could do with the plugin.  The plugin itself only provides supplementary api endpoints Klaviyo needs as well as snippets on the live woocommerce pages like Active on Site and Viewed Product events.