Here is the link for the Sig Romeo 5 Tread in this video: https://amzn.to/2LuDXTf
This video demonstrates how to disassemble and remove the factory folding stock on an AK M70-pattern underfolder [AK-47] and replace it with an M4-style stock using the Definitive Arms UFM4-AKMS stock adapter.
While this particular firearm is a Century Arms Yugo AKM70AB2, the process of removing the factory stock is similar for any underfolding AK/AKM [M70, M70AB, M70AB2, etc].
This video shows detailed disassembly instructions of the underfolding stock locking mechanism, pin removal, and replacement with a fixed/telescopic M4 stock.
The adapter can be purchased from Copper Custom Armament.