Skip request based on condition (collection)

I agree with what @praveendvd said. What you could possible do is create a set of environment variables for which types of requests you want to run.
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In your pre-request script (you could even do this at the collection level so you didn’t have to repeat it for every request) you can use the following script:

if(pm.request.method === 'GET' && !pm.environment.get('executeGETRequests') {
  pm.request.url = 'https://www.postman-echo.com/delay/0';
} 
else if(pm.request.method === 'PUT' && !pm.environment.get('executePUTRequests') {
  pm.request.url = 'https://www.postman-echo.com/delay/0';
  pm.request.method = 'GET';
}
else if(pm.request.method === 'POST' && !pm.environment.get('executePOSTRequests') {
  pm.request.url = 'https://www.postman-echo.com/delay/0';
  pm.request.method = 'GET';
}
else if(pm.request.method === 'DELETE' && !pm.environment.get('executeDELETERequests') {
  pm.request.url = 'https://www.postman-echo.com/delay/0';
  pm.request.method = 'GET';
}

This script will check if the request is a specific HTTP method, check your environment variable to see if it should execute, and if it’s not allowed, change the request to hit the postman echo API - which is essentially a no-op. It does not permanently change your request, just that specific execution.