The ability to change the channel is a function of the wifi adapter driver. Some can, some can't.
If yours can, you'll find it in the wifi adapter properties.
Press the Windows logo and "R" keys simultaneously to display the "Run" dialog box. Type "devmgmt.msc" without quotation marks into the
box and press "Enter." The Windows device manager will appear.
Double-click "Network Adapters" to expand the category.
Right-click your wireless network adapter and click "Properties."
Click the "Advanced" tab, then click "Ad Hoc Channel 802.11" under "Property" on the left side of the window.
Use the arrows on the right side of the window to change the channel. Make sure that you and your ad hoc networking partner select
the same channel.
Click "OK" to save the change, then close the device manager.
source