delete partition but not the data from partition

Database
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delete partition but not the data from partition

I have a table t1 which is partitioned by rptg_dt column for interval as 1 day

I want to remove the partitions(partition number) but not the data from partition.

(i.e. table structure modification but not to delete records present in each partition)

Is there any syntax  or I have to follow the below mentioned approach.

Create a new table t1_x. with same structure of t1 withing having partitioned clause.

load data from t1 to t1_x. drop t1. rename t1_x to t1.