Disabling 802.11g on THAT AP is easy however if your client/device population comprises of 2.4ghz band based then doing this may end up creating a coverage hole. Here is how we do it --> http://prntscr.com/3fewiw
If i would be in your place then would follow the below steps:
1. Find out the real culprit and remove it (if possible) Or if change its frequency/channel.
2. Use interference avoiding mechanism like Channelfly.
Read more here on channelfly--> http://c541678.r78.cf2.rackcdn.com/fe...
How to use channelfly, see here - http://prntscr.com/3ff7o5
btw from you stats on the suspect AP:
802.11g/n NoiseFloor: -112, PHY Errors 43992, %AirTime (total/busy/RX/TX) 67.7/33.9/25.9/8.2
Busy % of 34 % indicates that 34% of time AP is spending its strength in interpreting noise or something non-wifi may be from security sensor etc
Use of channelfly will correct things for you however in the initial few days of channelfly would cause client disconnects as it reads the environment and make a sound channel selection.
Hope it helps