How to get rid of other wi fi network

If you go to wifi > settings, select the one you no longer need, there should be a "forget this network" option. Select "forget this network", read the message on the prompt to confirm you want to forget it, and then select “forget.” This will then stop automatically connecting to this network, but as the other comment states, if that network is still available and in range it will still appear in the list.

when you go into settings->wifi it will under networks show all wifi networks within range unless the wifi network is set to not broadcast ssid, that is how wifi works on all devices from computers to phones