I still get the error when I try any method. The column names with spaces are throwing error 

[DELTA_INVALID_CHARACTERS_IN_COLUMN_NAMES] Found invalid character(s) among ' ,;{}()\n\t=' in the column names of your schema.

df1.write.format("delta") \
.mode("overwrite") \
.option("mergeSchema", 'true') \
.option("delta.columnMapping.mode", "name") \
.option('delta.minReaderVersion', '2') \
.option('delta.minWriterVersion', '5') \
.option("path","/tmp/spark-delta-table") \
.saveAsTable("`spark-delta-table`")

 Or

df1.write.format("delta") \
.mode("overwrite") \
.option("mergeSchema", 'true') \
.option("delta.columnMapping.mode", "name") \
.option('delta.minReaderVersion', '2') \
.option('delta.minWriterVersion', '5') \
.save("/tmp/spark-delta-table")