Final answer:
The command 'no access-list 10' removes the specified Access Control List from the network device, ceasing its packet filtering rules and potentially altering the network's traffic flow.
Step-by-step explanation:
When a network administrator enters the command no access-list 10 into a router or switch, they are instructing the device to delete the Access Control List (ACL) labeled as number 10. ACLs are used to control the flow of packets into or out of a network device, and they consist of a series of rules that either permit or deny traffic based on specific criteria such as IP address or port number. The effect of removing an ACL is that the rules it contained are no longer applied to packet filtering decisions, potentially opening the network to any traffic that the deleted ACL was designed to block or restrict.