You can do this by following one of the two methods below:

1- Use the "Alliance Teleport" item if you have it, and your city will be instantly moved to a location near your alliance leader.

2- Tap the Alliance icon at the bottom right of the screen, then tap the "Teleport" icon at the bottom of the Alliance screen. 
You will be instantly directed to a location near your alliance leader on the map. 
You can use the "Alliance Transfer" item if available, or buy and use Diamonds to confirm the Teleport