I have a database with only a collection. But FileSize of the UserDb db is huge, and there are lots of files on linux filesytem and disk' util% is high. How to reclaim or purge it.

PRIMARY> show tables
loginStatus
system.indexes
PRIMARY> db.loginStatus.stats()
{
"ns" : "UserDb.loginStatus",
"count" : 57737693,
"size" : 8290810936,
"avgObjSize" : 143.59442688505064,
"storageSize" : 35528597328,
"numExtents" : 47,
"nindexes" : 4,
"lastExtentSize" : 2146426864,
"paddingFactor" : 1,
"flags" : 1,
"totalIndexSize" : 16614400544,
"indexSizes" :

{ "_id_" : 1873489520, "Time_1_SoftwareVer_1_Resource_1" : 3683884848, "UserId_1" : 5463791872, "Time_1_UserId_1" : 5593234304 }

,
"ok" : 1
}
PRIMARY> db.stats()
{
"db" : "UserDb",
"collections" : 3,
"objects" : 58491118,
"avgObjSize" : 143.59493302897715,
"dataSize" : 8399028172,
"storageSize" : 35528613712,
"numExtents" : 49,
"indexes" : 4,
"indexSize" : 16834547520,
"fileSize" : 102962823168,
"nsSizeMB" : 16,
"ok" : 1
}

ls /data/mongodb/data/UserDb/
_tmp UserDb.13 UserDb.19 UserDb.24 UserDb.3 UserDb.35 UserDb.40 UserDb.46 UserDb.51
UserDb.0 UserDb.14 UserDb.2 UserDb.25 UserDb.30 UserDb.36 UserDb.41 UserDb.47 UserDb.6
UserDb.1 UserDb.15 UserDb.20 UserDb.26 UserDb.31 UserDb.37 UserDb.42 UserDb.48 UserDb.7
UserDb.10 UserDb.16 UserDb.21 UserDb.27 UserDb.32 UserDb.38 UserDb.43 UserDb.49 UserDb.8
UserDb.11 UserDb.17 UserDb.22 UserDb.28 UserDb.33 UserDb.39 UserDb.44 UserDb.5 UserDb.9
UserDb.12 UserDb.18 UserDb.23 UserDb.29 UserDb.34 UserDb.4 UserDb.45 UserDb.50 UserDb.ns