Undo other users checkout
1. Log in as Tfs Admin
2. Launch Visual studio command prompt
3. use the below Undo workspace command.
tf undo /workspace:userxyzworkpacename "$/Silver/Documents/Project Management/Sprint 12/*.*" /s:https://servername:8080/TFS/[ProjectCollectionName]
4.For recursively deleting all files under the folder use
tf undo /workspace:userxyzworkpacename "$/Silver/Documents/Project Management/Sprint 12/" /s:https://servername:8080/TFS/[ProjectCollectionName] /RECURSIVE