1) Open Blender
2) [Top left-hand corner] "File" > "Import" > [Chose the correct format (extension is in brackets)] > [Find and open the model]
3) Right-Click The Model so the mesh is selected and not the bones
4) Press "Tab" to go into edit mode
5) Select the vertices of the 3 extra shurikens and press delete
5a) [Optional] remove any bones which were part of the shurikens
6) Export the model ["File" > "Export" > "FBX"] or just save it because Unity accepts .blend ["File" > "Save As"]
Note:
(06-27-2018, 06:05 AM)skylanderartist Wrote: ...I noticed that there was one problem there were 3 extra shurikens on the back and there should only be 1...
You are incorrect, that is not a problem with the model, those extra shurikens are for animation purposes, its just by default they are placed like that but, when Ash-Greninja's Idle animation is played they are disabled and are only re-enabled when you use its signature move.