We would simply need to remove Russia from SWIFT:
https://en.wikipedia.org/wiki/Societ...ecommunication
Then all russian banks go down, russians cant buy anything online, use credit cards, order things from abroad, they basically become completely isolated from world's financial system.
The West didn't bring down russian economy because destroying countries is, as amazing is sounds to you, something the West doesn't enjoy. They prefer diplomacy over everything else, and have tradition of sticking to it for ever too long, when other measures would be more appropriate.