Oracle Error: ORA-00054 - resource busy and acquire with NOWAIT

Today I tried to create an INDEX over 2 columns where one of them were already indexed. After receiving the error ORA-00054 - resource busy and acquire with NOWAIT I needed some time that this is because of previous used INDEX.

Previously used index:
CREATE INDEX index_name ON table_name
(
column_name ASC
)
/

wanted to change it to the following:
CREATE INDEX index_name ON table_name
(
column_name1,column_name2
)
/

all I needed to do were to delete previous INDEX and then it run fine - maybe this is not at any scenario correctly to do but for my case it worked out.