MyEclipse Unable to delete files under Project

Want to delete the old version of the jar package or file, but how also can not delete, always prompt problems encountered while deleting resources. Could Not Delete

Later off MyEclipse Restart MyEclipse still can't delete, finally shut down myeclipse, delete the source file on the local hard drive, should be the Java Virtual machine occupies the file resulting in unable to delete, then shut down the Java virtual machine, and then delete, quite helpless, Later with this version of the MyEclipse can not delete documents.

MyEclipse Unable to delete files under Project