To modify egress rate parameters you can simply apply an egress-rate command with new egress-rate and max-burst value.
The following is a sample configuration that shows a modified egress-rate configuration for a port.
*A:Dut-1>config>port# ethernet egress-rate 10000 max-burst default
*A:Dut-1>config>port# info
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ethernet
egress-rate 10000
exit
no shutdown
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*A:Dut-1>config>port#