Before creating the word document, you can can close the process WINWORD.EXE by placing the following code:
CreateObject("WScript.Shell").Run "taskkill /f /im WINWORD.EXE", 0
After doing this, you can proceed with the word file creation. Even if there are multiple processes running, they are all terminated.
Here, /f indicates the forceful deletion of process and /im indicates that we are passing the process name(WINWORD.EXE in this case).
To know more about the taskkill command, you can refer this site: https://technet.microsoft.com/en-in/library/bb491009.aspx
EDIT 2:
If there are multiple documents open and you want to close only one of them then, you can write the following codes to close that particular document:
Case 1: When you know the exact path of the word file to be closed
strPath = "store the word file path in this variable"
set objDoc = getobject(strPath)
objDoc.close
set objDoc = Nothing
Case 2: When you only know the name(let's say the name is Document1) and not the path
set objWord = getobject(,"word.application")
set objDocs = objWord.Documents
for each doc in objDocs
If strComp(doc.name,"Document1",1)=0 then
doc.close
Exit For
End If
next
set objDocs = Nothing
set objWord = Nothing