I am an absolute Photoshop novice but I need to convert my 3 color logo to 2 colors to save on printing costs. The PMS colors in my logo are Pantone 158 U (orange), Pantone 361 U (green), Pantone 7546 U (gray- this includes a few different shades). The logo was produced by a logo creation service but I am hesitant to go back to them to ask for assistance (cost!).

I definitely need to keep the orange and green but I am told that I can screen or blend the green to get it to almost look gray while maintaining the core green PMS color. What would be the best way to achieve this?? Any help would be greatly appreciated.