You can find Factory reset function inside Special Task button in main tab.
This factory reset button basically formatting the userdata and cache partition.
So, you can perform manually if the button I mention is not available by doing formatting above partition,
or by direct write userdata.img and cache.img from your firmware folder. This is also factory reset operation.
Unfortunately you can't flash oppo in UFS ToolBox.
You may try to recover it using Android ToolBox for flashig operation.